It is becoming increasingly important to provide devices for converting solar energy to electrical energy as sources of organic materials are depleted. The current photovoltaic cells formed of silicon having a PN junction under the surface thereof are expensive to manufacture and rather delicate to operate. For example, these devices must be maintained within rather close temperature tolerances and in the event high temperatures are encountered, the functioning of such devices degrades substantially. Typical prior art devices of the type above referred to are shown and described in U.S. Pat. Nos. 4,001,864; 3,904,453; 3,943,003; 3,977,905 and 4,029,518. Applicant herein is the inventor of the invention described and claimed in U.S. Pat. No. 3,828,186.
It has been a particular problem in the art to provide a high voltage photovoltaic cell, e.g., a cell with a voltage level of, say, 1.5 to 3 or more volts, without sacrificing current generating capacity of the cells. Most photovoltaic materials of the prior art capable of generating even moderately improved voltage output do not respond to relatively low-energy photons, normally plentiful in sunlight, and, as a result, the total current drops substantially. Yet a high voltage is highly desirable to minimize problems and costs associated with converting the photovoltaic output into external energy distribution systems.